var async = require('async')
console.time("auto方法");
	async.auto({
    task1: function(callback){
    	console.log("tsak1");
    	setTimeout(function(){
	      callback(null, 'task11', 'task12');
	    },2000);
    },
    task2: function(callback){ 
    	console.log('task2');
    	setTimeout(function(){       
	      callback(null, 'task2');
	    },3000);
    },
    task3: ['task1', 'task2', function(callback, results){
    	console.log('task3');
    	console.log('task1和task2运行结果: ',results);
    	setTimeout(function(){        
	      callback(null, 'task3');
	    },1000);
    }],
    task4: ['task3', function(callback, results){
    	console.log('task4');
    	console.log('task1,task2,task3运行结果: ',results);
    	setTimeout(function(){
      	callback(null, {'task41':results.task3, 'task42':'task42'});
      },1000);
    }]
	}, function(err, results) {
    console.log('err :', err);
    console.log('最终results : ', results);
    console.timeEnd("auto方法");
	});
